Production of cycloalkadiene hydrocarbons



Patented May 1 1, 1954 PRODUCTION OF CYCLOALKADIENE HYDROCARBON S CarlB. Linn, Riverside, Ill., assignor to Universal Oil Products Company,Chicago, 111., a corporation of Delaware No Drawing. Application October28, 1950, Serial No. 192,825

This application is a continuation-in-part of my co-pending application,Serial Number 751,127, filed May 28, 1947, now abandoned This inventionrelates to a process for producing cycloalkadiene hydrocarbons andparticularly for producing a conjugated cyclohexadiene. An object ofthis invention is to form a cycloalkadiene hydrocarbon.

Another object of this invention is to form a cyclohexadiene.

Still another object of this invention is to form cyclohexadiene-1,3.

A further object of this invention is to form cyclohexadiene-1,4.

One embodiment of this invention relates to a process for producingcyclohexadiene which comprises reacting a mixture of a cyclohexenone andcyclohexenol in the presence of an aqueous solution of an acid-actingcatalyst and recovering the resultant cyclohexadiene.

Another embodiment of this invention relates to a process for producingcyclohexadiene which comprises reacting a mixture of a cyclohexenone anda cyclohexenol in the presence of an aqueous solution of a mineral acid.

A further embodiment of this invention relates to a process forproducing cyclohexadiene which I relates to a process for producingcyclohexadiene which comprises reacting a, mixture of a cyclohexenoneand a cyclohexenol in the presence of an aqueous solution of magnesiumchloride.

This invention relates to a process for preparing a cyclohexadienehydrocarbon from a cyclohexene hydrocarbon by a combination of oxidationand dehydration reactions. This process may be applyied to differentcyclohexene hydrocarbons including cyclohexene and various alkylated andsubstituted cyclohexene hydrocarbons having a hydrogen atom combinedwith each of the doubly bonded carbon atoms.

Cyclohexene and other cyclohexene hydrocarbons which are utilizable asstarting materials in this process, are reacted with gaseous oxygen orwith a gas containing free oxygen at a temperature of from about 100 toabout 225 C. and preferaoly at a temperature of from about 125 to about175 C. and at a superatmospheric pressure up to about 100 atmospherespreferably 25 to 75 atmospheres. The resultant oxidation productconsists of about60% of unconverted cyclohexene which is suitable forrecycling to the process and 3 Claims. (01. 260-666) may be reacted toform cyclohexadiene.

40% of oxygen-containing organic material boiling above C. atatmospheric pressure. This oxygen-containing organic material whichcomprises essentially cyclohexenone and cyclohexenol when cyclohexeneitself is the starting material, Other cycloalkenes may be oxidizedsimilarly by free oxygen to form cycloalkenones and cycloalkenols.Distillation or the resultant oxygen-containing organic material atatmospheric pressure gives a distillate which contains a mixture ofcyclohexadiene isomers boiling from about 78 to about 83 C. andequivalent to from about 20 to about 30% of the weight of theoxygen-containing material treated.

When the oxygen-containing organic material is distilled at asubatmospheric pressure, a, mixture of cyclohexenone and cyclohexenolboiling at to C. at 1 atm. pressure is obtained in an amount equivalentto 50-70% by weight of the oxygen-containing organic material. Themixture of cyclohexenone and cyclohexenol is converted intocycloheXadiene-1,3 in almost 100% yield by heating at a temperature offrom about 100 to about 200 C. and preferably at C. with a diluteaqueous solution of magnesium chloride. Distillation of the mixture ofcyclohexenone and cypclohexenol with dilute sulfuric acid also gaveabout 100% yield of cyclohexadiene, but in this case, the cyclohexadieneconsisted of a mixture of isomers.

According to this process, a cyclohexene hydrocarbon and particularlycyclohexene itself is oxidized either continuously or in batch-typeoperation at a temperature near 150 C. and a pressure of 1 to 100 atms.Air may be used as the oxidizing agent or a more pure source of oxygenmay be employed. It is of importance that the mole ratio of cyclohexeneto oxygen exceed 2 and preferably be in the range of 4 to 10. Theproduct obtained from this oxidation treatment is also dependent uponthe method used and its recovery. By employing reduced pressure for itsdistillatioh, cyclohexenol is the main product but if the gen ions dueto distillation in the presence of a dilute aqueous solution of amineral acid or of an acid-acting salt.

The importance of asimple and relatively inexpensive synthesis ofcyclohexadiene is app parent, since this material was previouslyavailable only by a long chemical synthesis. Cyclohexadiene has greatpotential use in chemical synthesis as its conjugated unsaturationpermits its use in polymerization and condensation reactions leading tothe formation of long chain molecules such as those present in rubber,plastics and resins The nature of the present invention and type ofresults obtained thereby are indicated further by the following exampleswhich should not be misconstrued to limit the broad scope of the invention.

Example I A 3.8 liter rotatable steel autoclave was charged with 100 m1.(325 rams) of cyclohexene, and air was added to a pressure of 35 atms.to give an oxygen charge of approximately 32 grams. The temperature ofthe autoclave was increased slowly to 145 C. when reaction was evidencedby a slight explosion which caused the self-generated pressure toincrease rapidly by several atmospheres. The autoclave was cooled and 90liters of gas were released which analyzed 96% by volume of nitrogen andcontained small amounts of oxygen, carbon monoxide, carbon dioxide andhydrogen. The liquid recovered from the autoclave (340 grams) wasdistilled at reduced pressure (8 mm.) and separated into the followingfraction (B. P. converted to 1 atmos.):

Per cent Unreacted cyclohexene 58.1 Material boiling near 160 a 20.1Material boiling near 205 b 7.0 Adip-ic acid 1.7 Other liquid products7.0 Carbon oxides, water and loss 6.1

Mostly cyclohexenol.

Mostly cyclohexanediol-1,2. When the product recovered from theautoclave was distilled at atmospheric pressure, less material wasobtained boiling at 160 C. probably because more of the oxygen-containinmaterial had been decomposed to cyclohexadiene-1,3 as evidenced byphysical constants and formation of an addition product with maleicanhydride.

Example II In another run, a 3.8 liter rotatable steel autoclave wascharged with 325 grains of cyclohexene and air-was added to a pressureof 35 atms. The autoclave heated to 150 C. and then cooled. The residualpressure was released without measuring or analyzin the eliiuent and theresultant liquid product was collected. The liquid products from thisrun and from other similar runs were blended and distilled. A compositesummary was as follows:

Total charge, grams:

Corresponds to cyclohexenone+cyclohexenol. These data show a 35%conversion of cyclo- To a min. T Corr. to Wt., Per- Fraction Hg 0 cent 8-98 Bott0ms Above 98.... 16

Cyclohexene oxidizes to give a high yield of material boiling near 160;this decomposes thermally to give a material boiling near 80 which iscyclohexadiene. A crystalline fraction boiling near 200 iscyclohexane-di-oLl-Z.

In another run a sizable quantity of the cyclohexene oxidation productwas prepared as follows:

Under the conditions of reaction (150 C. With a cyclohexen to oxygenmolar ratio of 4) 1.35

1015 cyclohexene reacted per mole oxygen. On a weight basis, 61% of theproduct was recycle cyclohexene; 39% (I), was higher boiling thancyclohexene.

(I) was distilled at 1 atmosphere through a Nichrome packed column,taking the overhead temperature to 271 0.; 82% (II), was volatile.Decomposition of (1') was occurring durin the distillation as evidencedby erratic overhead temperature. (II) distilled and showed a 22% contentof organic material boiling at 79-85 which appeared to be a mixture of1,3-, and 1,4-cyclohexadiene in about equal amounts. Thus 18% of .(I)was recovered as cyclohexadiene.

When (I) was distilled at 8 mm. pressure, 55 (III) boiled near 68 and nodecomposition to the diene occurred. When redistilled at 1 atmosphere ina glass system, product (III) boiled near 164.

(III) was hydrogenated at 42 in presence of a nickel catalyst to giveapparently quantitative yield of cyclohexanol.

x111) examined by infrared analysis showed presence of (a) a cyclchexenederivative containing an (DH); (by a cyclohexene derivative containing a(C 0). ((1) and (b) appeared to be present in nearly equal amounts.

(III) was used to prepare a phenylurethan which melted correctly for thecorresponding derivative of cyclohexene-1,3-ol.

(III) was treated in an autoclave for 2 hours with equal volume ofaqueous solution, containing 2% of magnesium chloride.

(a) At 100 no cyclohexenol formed; about 50% was unchanged, the restapparently condensed.

(b) At 26% of III was converted to cyclohexadiene which ultravioletanalysis indicated to be nearly all the 1,3-isomer.

(I) was treated with a very dilute solution of sulfuric acid (about 1%'I-IzSO4) and the twophase system was distilled. 22% of (I) charged wasconverted and finally recovered as cyclohexa- .diene, the two isomers inabout equal amounts.

claim as my invention:

1. A process for producing cyclohexadiene which comprises reacting amixture of a cyclohexenone and a cyclohexenol at a temperature of fromabout 100 to about 200 C. in the presence of an aqueous solution of anacid-acting catalyst selected from the group consisting of sulfuric acidand magnesium chloride and recovence of an aqueous solution of magnesiumchloride.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,164,647 Hibbert Dec. 21, 1915 2,291,915 Palmer et a1. Aug.4, 1942 2,368,068 Morey Jan. 23, 1945 2,492,956 Ballard et a1. Jan. 3,1950 OTHER REFERENCES Journal Chem. Soc. (London), vol. 103 (1913), pp.1242-1250.

1. A PROCESS FOR PRODUCING CYCLOHEXADIENE WHICH COMPRISES REACTING AMIXTURE OF A CYCLOHEXENONE AND A CYCLOHEXENOL AT A TEMPERATURE OF FROMABOUT 100* TO ABOUT 200* C. IN THE PRESENCE OF AN AQUEOUS SOLUTION OF ANACID-ACTING CATALYST SELECTED FROM THE GROUP CONSISTING OF SULFURIC ACIDAND MAGNESIUM CHLORIDE AND RECOVERING THE RESULTANT CYCLOHEXADIENE.